> ## Documentation Index
> Fetch the complete documentation index at: https://docs.onsleek.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# API introduction

> Sleek API documentation for cashback and more.

## Base URL

As you browse the API documentation, you will note that the Sleek API is built on REST principles. We enforce HTTPS in every request to improve data security, integrity, and privacy. The API does not support HTTP.

All requests contain the following base URL:

```
https://api.onsleek.ai
```

## Authentication

All protected API endpoints are authenticated using Bearer tokens. To authenticate you need to add an *Authorization* header with the contents of the header being `Bearer 12345` where `12345` is your API Key.

```
Authorization: Bearer 12345
```

## Response codes

Sleek uses standard HTTP codes to indicate the success or failure of your requests.

In general, `2xx` HTTP codes correspond to success, `4xx` codes are for user-related failures, and `5xx` codes are for infrastructure issues.

| Status | Description                                                            |
| ------ | ---------------------------------------------------------------------- |
| 200    | Successful request.                                                    |
| 400    | URL parameters or body was invalid. Response body contains the errors. |
| 401    | The API key used was missing.                                          |
| 403    | Unauthorized to access resource.                                       |
| 404    | The resource was not found.                                            |
| 429    | The rate limit was exceeded.                                           |
| 5xx    | Indicates an error with Sleek servers.                                 |